1. Field of the Invention
The present invention relates to a protection circuit module for a rechargeable battery and to a battery provided with such a protective circuit module.
2. Description of the Related Art
A battery pack for use as a rechargeable power source of portable terminal equipment such as a cellular phone is provided with a protective circuit for preventing a rechargeable battery from overcharging or overdischarging. For convenience in assembling the battery pack, such a protective circuit is generally provided as a module.
FIG. 8 schematically illustrates an example of battery pack 30 comprising such a conventional protective circuit module 10 and a rechargeable battery 40 which are housed in a case 20.
The protective circuit module 10 basically comprises an insulating substrate 11 which is formed of e.g. glass-fiber-reinforced epoxy resin and has a surface on which electronic components for constituting a protective circuit are mounted and sealed by a molding 13, and conductor plates 14, 15 each having an end connected to the substrate 11 for connecting the protective circuit to the rechargeable battery 40. Each of the conductor plates 14 and 15 has another end connected to a positive electrode 41 or a negative electrode 42 provided on an outer shell of the rechargeable battery 40 by spot welding, for example. In the example shown in FIG. 8, a plurality of terminals 16 are formed on a surface of the substrate 11 opposite to the surface formed with the molding 13. With the protective circuit module 10 housed in the case 20, the terminals 16 are exposed to the outside through a window 21 formed in the case 20 for electrically connecting the battery pack 30 to the body of the portable terminal equipment. Through the terminals 16, charging current from a charger is supplied via the portable equipment body to the battery pack 30 and discharging current from the battery pack 30 is supplied to the portable equipment body.
The rechargeable battery 40 generally has a rectangular configuration having a predetermined thickness. Generally, the positive electrode 41 (or the negative electrode, which holds true hereinafter) is provided as a projection formed centrally on one of longitudinally opposite end surfaces of the battery, whereas the negative electrode 42 (or the positive electrode, which holds true hereinafter) comprises the entire conductor surface of the battery except the positive electrode. As shown in FIG. 8, to connect the conductor plate 14 to the positive electrode 41 in the form of a projection, the conductor plate need be bent at a right angle relative to the substrate 11 and again bent at a right angle to provide a portion 14b extending parallel to the end surface of the battery, and the portion 14b need be connected to the positive electrode 41 by spot welding.
As described above, since the entire outer shell of the rechargeable battery 40 except the positive electrode 41 constitutes the negative electrode, the horizontal portion 14B of the conductor plate 14 need be prevented from inadvertently coming into short-circuit contact with the outer shell of the battery. Generally, to cope with the need, a non-illustrated spacer is interposed between the protective circuit module 10 and the end surface 40a of the rechargeable battery 40.
However, such a coping method increases the number of parts of the battery pack 30 and deteriorates the efficiency in assembling the pack, which results in an increase in the manufacturing cost of the battery pack.